Both Decreased and Increased Heart Rate Variability on the Standard 10-Second Electrocardiogram Predict Cardiac Mortality in the Elderly: The Rotterdam Study

Abstract

Decreased heart rate variability has been associated with an adverse prognosis in patients after myocardial infarction. Studies carried out in the population at large show contradictory results. The authors examined the association between heart rate variability on a standard 10-second electrocardiogram and cardiac and all-cause mortality in the Rotterdam Study, a population-based cohort study of men and women aged > or =55 years, using data collected between 1990 and 1996 (mean follow-up = 4 years). Heart rate variability, taken as the standard deviation of normal R-R intervals (SDNN), was computed by means of the Modular ECG Analysis System. After exclusion of subjects with arrhythmia and those with fewer than six normal R-R intervals, the study population consisted of 2,088 men and 3,184 women. Cox's proportional hazards model was used to examine the age- and sex-adjusted risk for cardiac, noncardiac, and total mortality in relation to quartiles of SDNN, using the third quartile of SDNN as the reference category. Subjects in the lowest quartile of SDNN relative to those in the third quartile had an 80 percent age- and sex-adjusted increased risk for cardiac mortality (hazard ratio = 1.8; 95% confidence interval: 1.0, 3.2). Interestingly, for subjects in the highest quartile of SDNN, an even more pronounced risk for cardiac mortality was present (hazard ratio = 2.3; 95% confidence interval: 1.3, 4.0). Additional adjustment for possible confounders did not materially change the risk estimates. The authors conclude that heart rate variability measured on the standard 10-second electrocardiogram can be used to identify older men and women with an increased risk for cardiac mortality. In the elderly, increased heart rate variability is an even stronger indicator of cardiac mortality than decreased heart rate variability. Further studies are needed to confirm these findings and to elucidate their physiologic meaning.

Particulate matter and heart rate variability among elderly retirees: the Baltimore 1998 PM study

“…In the Framingham Heart Study of 736 elderly subjects followed for 4 years, Tsuji et al ( 1994 ) found a one standard deviation decrement in low-frequency power was associated with increased mortality (rate ratio = 1.7, 95% CI 1.4 to 2.1) . In a recent study of 5272 Dutch men and women aged 55 years and older who were followed for an average of 4 years, de Bruyne et al (1999 ) found that subjects in the lowest quartile of HRV ( standard deviation of normal RR intervals of 9.6 ms or less ) had a greater mortality rate (rate ratio =1.8, 95% CI 1.0 to 3.2 ) than subjects in the third quartile (standard deviation of normal RR intervals between 15.2 and 25.9 ms ). In another Dutch study of 878 men aged 40 to 60 years at enrollment followed for 30 years, Dekker et al ( 1997 ) found increased mortality (rate ratio= 2.1, 95% CI 1.4 to 3.0) among 96 subjects with low HRV (standard deviation of normal RR intervals of 20 ms or less ) .…”

Heart Rate Variability: An Index of the Brain-Heart Interaction

“…In the elderly, some studies showed that higher heart rate variability is stronger indicator of cardiac mortality than decreased heart rate variability. Further studies are needed to confirm these findings and to elucidate their physiologic meaning (de Bruyne et al, 1999).…”

Modulation of QT Interval During Autonomic Nervous System Blockade in Humans

“…2,3 Accordingly, determination of QT interval length in the surface ECG corrected for heart rate (QTc) is commonly used for risk stratification in clinical studies. The QT interval reflects depolarization and repolarization of myocardial cells.…”